1. Field of the Invention
The present invention relates to an endoscope system that forms illumination light for illuminating an observation target using light sources of a plurality of colors, a light source device, an operation method for an endoscope system, and an operation method for a light source device.
2. Description of the Related Art
In the medical field, diagnosis using an endoscope system including a light source device, an endoscope, and a processor device has been widely performed. The light source device is a device that generates illumination light emitted to the observation target, such as a mucosa of the body cavity. As the light source device, not only is a broadband light source, such as a xenon lamp or a white light emitting diode (LED), used, but also semiconductor light sources of a plurality of colors, such as a blue LED, a green LED, and a red LED, have been used in combination with each other in recent years.
For example, in the endoscope system disclosed in JP-2013-255655A, four semiconductor light sources that are independently controllable are mounted in a light source device. The spectrum (light intensity distribution for each wavelength) of illumination light is adjusted by controlling the amount of light emitted from each of the four semiconductor light sources, so that the observation target can be irradiated with illumination light having optimal characteristics according to image characteristics to be acquired. Specifically, in order to obtain an image having a large dynamic range for brightness, an image with a low color temperature, an image with a high color temperature, and an image when irradiating a narrow region with special narrow-band wavelength light, the spectrum of illumination light or the like is adjusted.
The endoscope system disclosed in JP-2007-139822A includes an LED that emits visible light and an LED that emits ultraviolet light. By emitting not only the visible light but also the ultraviolet light, a wound on which fluorescent paint applied in advance is accumulated becomes noticeable by the fluorescent light.
In addition, an endoscope system that acquires not only an image of the observation target but also information indicating the characteristics of the observation target has been known in recent years. For example, in the endoscope system disclosed in JP5303012B, the oxygen saturation is measured as a characteristic of the observation target by irradiating the observation target with oxygen saturation measurement light (hereinafter, referred to as measurement light) having a wavelength band in which there is a difference between the absorption coefficient of oxygenated hemoglobin and the absorption coefficient of reduced hemoglobin, and an image showing the oxygen saturation (hereinafter, referred to as an oxygen saturation image) is generated and displayed.